The green alga Volvox carteri is unique among microorganisms in producing a large number of terminally differentiated somatic cells as a regular feature of each cycle of asexual reproduction. These cells go through a precise sequence of development and eventual senescence. This sequence of events is intrinsic to the individual cells and suggests a sequential genetic program. The genetics and biochemistry of development and subsequent senescence of Volvox somatic cells will be investigated. Non-senescent mutants of the organism will be selected and analyzed phenotypically and genetically. Stage-specific synthesis and export of the glycoprotein sheath material produced by somatic cells will be monitored. Synthesis of DNA and ribosomal RNA during senescence will be investigated by radioactive labelling and polyacrylamide gel electrophoresis. Poly-A RNA will be analyzed by tritiated Poly-U hybridization and column binding. Protein synthetic patterns will be analyzed by 2-dimensional polyacrylamide gel electrophoresis and compared in wild-type and non-senescent mutants. Biochemical changes during senescence will be correlated, where possible, to ultrastructural changes. The overall object of the study is to provide basic information on the role of genetic programming in development and senescence.